A theory of transfer ionization: application to He++Mg to He+Mg+2+e-

Abstract

A theoretical investigation has been conducted to the exothermic transfer ionization reaction, He⁺+Mg to He+Mg²⁺+e^-. The mechanisms assumed is autoionization of the diatomic ion HeMg⁺. To compute the potential energy curves and autoionization width descriptive of this process, Hartree-Fock single-configuration electronic wave-functions have been constructed for the initial discrete state, He⁺-Mg, and for the final continuum state, He-Mg⁺²-e^-. As the internuclear separation varies from 3 to 5 bohr, the lifetime for autoionization grows from 8.75*10^-14 to 3.2*10^-13 s. The cross section for transfer ionization has been computed according to Miller's classical trajectory theory of Penning ionization. This cross section reaches a maximum value of 12.9 a₀² for a collision energy equal to 1 hartree. Because of the inadequacy of our approximate potential energy function for the initial state, the theoretical cross section the authors have computed here is believed to be unreliable for energies less than this value.